Randy Holmes-Farley
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My Tank Thread
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In a recent thread, the topic came up whether it is cheaper to maintain calcium and alkalinity by water change or by dosing.
Water changes are always far more expensive, as seen below, although folks may be doing them for other reasons anyway, in which case one might consider it to be free.
I thought I’d start a separate thread to record some calculations to show how much cheaper dosing is than water changes.
Note that the relative result is independent of tank size, but this calculation says nothing about ease of doing either one nor am I making a claim about what is best to do (which may vary by tank size).
I will assume a 100 gallon total water volume system, and will look at alk rises from 7 dKH to 8, 9, or 10 dKH. Folks can scale the results to whatever size interested then.
I will choose a top end supplement, ESV B-ionic and a high end high alk salt mix, Red Sea Coral Pro. As a note, the higher the alk in the salt mix the less is needed, hence the choice of a high alk mix to reduce it’s apparent costs.
Right now, BRS sells 1 gallon ESV B-ionic mixes for $33.14 and a 200 gallon Coral Pro container for 79.99. No cost is added for the RO/di to make the salt mix.
Assuming the salt mix has 12 dKH as Red Sea claims, then it takes the following:
7-8 dKH, 20% change, 20 gallons needed, $8.00 cost
7-9 dKH, 40% change, 40 gallons needed, $16.00 cost
7-10 dKH, 60% change, 60 gallons needed, $24.00 cost
Doing a similar calculation for the ESV, we find that a 1 dKH boost takes 48.3 mL. That gives use these results:
7-8 dKH, 48.3 mL, $0.42 cost
7-9 dKH, 96.6 mL, $0.85 cost
7-10 dKH, 144.9 mL, $1.27 cost
We can see from these calculations that the cost of maintaining alk in these two ways is 19 times higher when accomplishing it by water change.
Water changes are always far more expensive, as seen below, although folks may be doing them for other reasons anyway, in which case one might consider it to be free.
I thought I’d start a separate thread to record some calculations to show how much cheaper dosing is than water changes.
Note that the relative result is independent of tank size, but this calculation says nothing about ease of doing either one nor am I making a claim about what is best to do (which may vary by tank size).
I will assume a 100 gallon total water volume system, and will look at alk rises from 7 dKH to 8, 9, or 10 dKH. Folks can scale the results to whatever size interested then.
I will choose a top end supplement, ESV B-ionic and a high end high alk salt mix, Red Sea Coral Pro. As a note, the higher the alk in the salt mix the less is needed, hence the choice of a high alk mix to reduce it’s apparent costs.
Right now, BRS sells 1 gallon ESV B-ionic mixes for $33.14 and a 200 gallon Coral Pro container for 79.99. No cost is added for the RO/di to make the salt mix.
Assuming the salt mix has 12 dKH as Red Sea claims, then it takes the following:
7-8 dKH, 20% change, 20 gallons needed, $8.00 cost
7-9 dKH, 40% change, 40 gallons needed, $16.00 cost
7-10 dKH, 60% change, 60 gallons needed, $24.00 cost
Doing a similar calculation for the ESV, we find that a 1 dKH boost takes 48.3 mL. That gives use these results:
7-8 dKH, 48.3 mL, $0.42 cost
7-9 dKH, 96.6 mL, $0.85 cost
7-10 dKH, 144.9 mL, $1.27 cost
We can see from these calculations that the cost of maintaining alk in these two ways is 19 times higher when accomplishing it by water change.